Tailplane stall is most likely to occur under which condition?

• A. In icing conditions with ice buildup on the tailplane.
• B. In dry air with clean wings.
• C. During maximum-speed cruise with ice-free wings.
• D. Only at extremely high altitudes.

Answer: (A)

Tailplane stall occurs when ice builds up on the horizontal stabilizer, altering the airfoil’s shape and flow. The ice roughens the tailplane and increases its effective angle of attack, causing flow separation and a loss of elevator effectiveness at conditions where you’re already near stall or operating with a high pitch. In icing conditions, the tailplane can rapidly accumulate ice, making a stall of the tailplane more likely than under clear-air, clean-wing conditions or at typical cruise speeds. The other scenarios—dry air with clean wings, high-speed cruise with ice-free wings, or simply extreme altitude—don’t provide the icy surface or the high-tailplane-AoA conditions needed for a tailplane stall, so the risk is substantially lower.